A road connecting a main line of a motor way or the like and a rest facility such as a service area or a parking area (including a facility with only a rest space without a building) (hereinafter referred to as “connection road”) is one-way; however, it is assumed that a vehicle may accidentally travel in a wrong direction when returning from the rest facility to the main line. In response to this, proposed is an onboard device for storing one-way information of roads in rest facilities or connection roads, comparing a direction in which travel is permitted in a one-way road near the position of a host vehicle with a traveling direction of the host vehicle, and notifying by speech or the like when it is determined that the host vehicle is traveling in a wrong direction (Patent Literature 1).
Also proposed is a system for determining whether a vehicle is traveling in a wrong direction by transmitting identification information from a wireless transmitter installed on a road side at a boundary between a rest facility and a connection road and receiving the identification information by a wireless receiver mounted on the vehicle and, when determination is made that the vehicle is traveling in the wrong direction, performing notification by speech or the like (Patent Literature 2).